Removed fill_last, contour and plot_kwargs arguments

[agustinaarroyuelo]

Description

This PR resolves #2073 by removing unused arguments from plot_pair

Checklist

• Follows official PR format
• Code style correct (follows pylint and black guidelines)
• Changes are listed in changelog

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📚 Documentation preview 📚: https://arviz--2085.org.readthedocs.build/en/2085/

[codecov]

Codecov Report

Merging #2085 (001aa8e) into main (fd27b97) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2085      +/-   ##
==========================================
+ Coverage   90.77%   90.78%   +0.01%     
==========================================
  Files         117      117              
  Lines       12488    12484       -4     
==========================================
- Hits        11336    11334       -2     
+ Misses       1152     1150       -2     

Impacted Files	Coverage Δ
arviz/plots/pairplot.py	92.00% <ø> (+3.11%)	⬆️

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[OriolAbril]

Looks great, thanks! I have added the issue to the right sidebar (on the development section) so it is closed automatically. I know that happens automatically if some keywords are used when mentioning the issue, will search for them, looks like addressed is not one of them

[OriolAbril]

Also, it is cool to see the rtd preview link injection working in the PR description! 🎉

📚 Documentation preview 📚 https://arviz--2085.org.readthedocs.build/en/2085/

Re keywords, it looks like is is fix, close, resolve (also valid in 3rd person present or past forms), reference: https://docs.github.com/en/issues/tracking-your-work-with-issues/linking-a-pull-request-to-an-issue#linking-a-pull-request-to-an-issue-using-a-keyword